The present invention relates to a method of recognizing spoken words, according to which method words are put in a dictionary in the form of vectors, the method comprising the following steps:
breakdown of the word to be recognized into input vectors, PA0 evaluation of ambient noise, PA0 choice of the word to be recognized from the words of the dictionary while said noise evaluation step is taken into account, via a choice of the dictionary word of which the distance that separates its input vectors from the reference vectors is the smallest, and PA0 validation of the word to be recognized by a comparison of said distance with a threshold value. PA0 modification of the threshold value as a function of the result of the evaluation of ambient noise.
The invention also relates to a system in which the method is applied, notably a wireless telephony device for cellular radiophone networks for which the hardware resources, memories and processors are on the whole assigned in limited manner. Such a method is described in European patent EP 0 750 292. According to this known method, the noise is estimated and all the vectors of the input signal and the vectors of the reference signals are modified as a function of this noise level into other vectors.
This known method is not very applicable to small-size devices in which the hardware resources are limited, notably the memory. Furthermore, these updates of the reference vectors take time causing delay which is annoying to the user of small devices.